Recently, display screens of electronic devices such as mobile telephones have become larger. When a plurality of pieces of different information are displayed on a display screen, it is possible to more effectively use the display screen. Japanese Patent Application Laid-Open No. 2007-241410 discloses a display device which can display a plurality of video images on a display device. The display device disclosed in Japanese Patent Application Laid-Open No. 2007-241410 divides the display screen into two based on a line segment defined by position coordinates of two points on the screen touched by the user within a predetermined time period and displays video images of different sources on the respective display screens.